Before planting it is a good idea to find your USDA Zone info to figure out your garden schedule. The zone info helps tell us things like average date of last frost and lowest expected temperature for your area.

The first chance to plant zinnia in Ottumwa should be figured out by using the USDA zone info.

Planting Calendar for Zinnia

Frost tolerance for zinnia:	Not tolerant of frost.
When to plant:	After the last frost has passed.

You really shouldn't plant zinnia until after the last frost when the weather gets warmer because they are not cold tolerant.

The earliest that you can plant zinnia in Ottumwa is April. However, you really should wait until May if you don't want to take any chances.

The last month that you can plant zinnia and expect a good harvest is probably August. You probably don't want to wait any later than that or else your zinnia may not have a chance to really do well. Starting your zinnia indoors is a great way to get them started a little bit earlier.

Last Frost Date

On average the last frost is on April 15 in Ottumwa. In the coldest months of winter you can expect an average low temperature of -15°F.

Since the USDA zone info for Ottumwa is an average the actual date of last frost changes from year to year. Since half of the time in Ottumwa last frost occurs after April 15 be ready to cover your zinnia if you have a late frost.

USDA Zone Info for Ottumwa

Here is the info for USDA Zone 5b.

Average Date of Last Frost (spring)	April 15
Average Date of First Frost (fall)	October 15
Lowest Expected Low	-15°F
Highest Expected Low	-10°F

This means that on a really cold year, the coldest it will get is -15°F. On most years you should be prepared to experience lows near -10°F.

Plants to Grow in Ottumwa

You may be interested in your other planting guides for Ottumwa.